Only a slight movement is needed ro check the brake caliper. A lot of movement would be an issue. You just want it to be able to float in a relaxed position when not needed. Binding would be bad as well.
Have you checked the front diff fluid? Or changed it in the past?
Is your truck 4wd. If so, does the TC engage and disengage properly? Does the noise get any worse if in 4-HI on grass or gravel, not pavement. Was AUTO 4wd used on a regular basis on dry pavement during its life?
Last suggestion would be to jack up all 4 wheels, put it in 4-HI, then let it idle in gear and listen for something similar to what you've experienced - inside and outside the vehicle. Sweep the steering left to right when wheels are spinning to test cv shafts for potential noise at extreme angles.